Image display device

Abstract

When a position detector detects that the position of a spot on a projection plane designates a non-projection region, the level of a driving signal of a laser is corrected. Specifically, the correlation between the quantity of laser light detected by a light-receiving portion and the level of the driving signal of the laser in accordance with prescribed data is detected. Then, the characteristic value of the laser indicated by the detected correlation is compared with the characteristic value at room temperature stored beforehand to indicate the correlation between the quantity of light emitted by the laser at room temperature and the level of the driving signal. Then, based on the comparison result, the level of the driving signal of the laser in accordance with image data is corrected.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to an image display device, and more particularly to an image display device displaying an image by applying laser light onto a projected plane.[0003]2. Description of the Background Art[0004]Image display devices displaying images by applying laser light onto projected planes such as screens or walls include so-called laser projectors. In a laser projector, laser lights of three primary colors of red, green and blue need to be prepared in order to reproduce images in full color. The configurations concerning image display using laser light in this manner are proposed in the followings.[0005]Japanese Patent Laying-Open No. 2003-005110 discloses an apparatus two-dimensionally scanning light, in which projection of a pattern used for sensing the quantity of light is prevented.[0006]Japanese Patent Laying-Open No. 2007-057555 discloses an image display device capable of displaying high-quality...

AI Technical Summary

Benefits of technology

The present invention provides an image display device that can adjust the quantity of light in response to changes in the output of a laser. The device includes a laser receiving a driving signal and outputting laser light with a quantity of light that depends on the driving signal level. An irradiation position control unit moves the spot of the laser light to the projection region based on image data. A position detection unit detects the position of the laser spot on the projection region, and a quantity of light detection unit detects the quantity of light output by the laser. A driving signal correction unit corrects the level of the driving signal based on the detected correlation between the quantity of light and the driving signal level. This allows for accurate control of the laser light output in the projection region, even if there are variations in laser output power. The correction is done by detecting the correlation between the quantity of light and a value indicating the correlation at room temperature, compensating for changes in laser temperature. This simplifies the device's configuration and reduces display image errors caused by laser output variations.

Problems solved by technology

As a result, the quantity of light which should be achieved for a prescribed gradation at room temperature cannot be achieved at a time of a temperature rise, so that the image quality of display images is reduced.

Moreover, special control is required so that an image according to the pattern information is not displayed, thereby complicating the configuration.

However, such a response characteristic change of a laser diode is not considered in correction.

Images